Issue started while mowing 2 acre lawn. Tried: new fuel and air filters, new plugs, new fuel pump. Still surging whether under load or not, at all throttle positions.
Surging on a governed engine is because the air fuel mixture is too lean to support a constant speed running
Either not enough fuel is getting in ( jets blocked, fuel tank outlet blocked etc etc ) or there is air getting in after the fuel has been added to the intake .